Radio tuning mechanism



March 21, 1944.

w. P. LEAR RADIO TUNING MECHANISM Filed Feb. 12, 1941 5 sheets-sheet 1 FDLPDO 191230 zoruzbm ATTORNEY March 2l, 1944. w. P. LEAR RADIO TUNING MECHANISM 'Filed Feb, 1.2, 1941 5 sneetsQseet 2 Y BY ATTORNEY March 2l, 1944. w- P LER I 2,344,825

' RADIO TUNING MECHANISM Filed Feb. 12, 1941 3 Sheets-Sheet 3 Jun uw l muh ATTORNEY Patented Mar. 21, 1944 RADIO |IYUNING MECHANISM William P. Lear, Dayton, Ohio, assignor, by mesne assignments, to Lear Avia, Inc., Piqua, Ohio, a corporation of Illinois Application February 12, 1941, Serial No. 378,490

s claims. icl. 11a-124.1)

invention relates to radio tuning systems,

and more particularly to improved arrangements for remotely controlling the operation and tuning of radio apparatus.

In accordance with the present invention, a control unit is provided remote from the main radio chassis for operating the band setting and tuningtherefor. A tuning indicator is provided for accurately indicating the frequency to which band selector and tuning control.

aiorded.

accompanying drawings, in which:

control unit.

l the housing removed.

3-3 of Fig. 1.

along the line 4.-4 of Fig."2.

Fig. 4. f

line 6-6 of Fig. 4.

- selector unit as seen at 1-1 of Fig. 3.

detail, taken along the line 8 8 of Fig. 2.

the radio` system is adjusted. A selector knob m cured to housingllbypins I4.

is used to connect the remote radio circuits for A function switch I is arranged to control operation on one of the plurality of radio bands, the circuital operation of the radio apparatus An important feature of the present invention is or direction finder in any one of several predeterthe novel tuning indicator coupled to both the mined conditions.

A curtain or l5 cated at follows: LOOP, referring to manual shutter is arranged to block out all but the tundirectional reception with a loop antenna only ing scaleA corresponding to the'selected band. (during static conditions); ANT,- for non-direc- The scales are relatively long and are mounted tional reception with a directional antenna only; on drums motivated by the tuning. The fre- ADF, for normal uni-directional automatic diquency indications on the long scales are thus -rection nder operation; and BDF, for autospread out so that a busy pilot has no diiculty matic bi-directional reception employing two in reading them. Accurate and convenient reloop antennae (during static conditions). mote control of a complex radio system is thus function switch'knob I5 is mechanically connected to four-position multiple-contact switch The above and other features, advantages, I6. Switch I6 contains a plurality of projectand capabilites of the invention will become ing lugs I6? which are suitably electrically conmore apparent in the following description of a nected to the remotely located radio chassis specic embodiment thereof illustrated in the through an electrical cable. Such cable is not indicated in the drawings. Fig. 1 is a front elevational view of the radio so unit through multiple contact plug IT. Details V of circuit connections of the control unit are not Fig. 2 is a rear view of the control unit, with illustrated, but are understood by those skilled in the art as dependent upon particular radio Fig. 3 is a plan view, partly in section, horicircuit arrangements employed. zontally across the control unit along the line A level or output control knob I8 is directly coupled to potentiometers contained within Fig. 4 is a horizontal cross-sectional view housing I9. The terminals of the potentiomthrough the tuning indicator mechanism, taker. eters are in circuit connection with plug I'I, for Y suitable connection in the radio circuit of the Fig. 5 is a vertical sectional view of the indx- 40 aforementioned cable. cator mechanism, taken' along the line 5-5 of With a Plug mate fr Plug I7 t0 Properly COIlDeCt with the electrical components. Fig. 6 is a, crossLsectional view through a. de- 2li is connected in the automatic volume control tail of the tuning mechanism, taken along the circuit of the set, or equivalent position for indicating the relative signal strength of the re- Fig. '7 is a rear view of the portion of the band ceived SgnaL Indicator 20 is in effect a relative distanceindicator or milemeter. VTerminals 2I Fig; 3 is an enlarged sectional view through a of meter 20 are respectivelyconnected in the cir- T cuit through cable 22. Meter 20 is mounted on The illustrated embodiment of the remote conpanel I0 by screws 23. trol unit islparticularly designed for a multiple l The direction finder or radio-apparatus is d;- band automatic radio direction nder system, signed for operation on a plurality of ranges or such as disclosed fin my Patent No.- 2.317.922 frequency bands. A band selector knob 25 isdated April 27, 1943, for Directional radio sysprovided to change the operation of the system 5 tem, which is assigned to the Vsame assignee as is this case. The control unit is rectangular in form, and made compact for placement on or at the pilots instrument panel of an aircraft. The remainder of the radio apparatus is remote therefrom. Referring particularly to Figs. 1, 2 and 3,l the control unit is enclosed by a panel I0 and a dust cover or casing II. The panel is attached to casing -II with screws I2 cooperating in threaded inserts I3. Inserts I3 are se- The It is attached to the The cable is provided An indicator to one of several predetermined radio frequency Four such positions are indibands. Six separate bands are shown in the illustrated embodiment, denoted by individual position numbers I to 6 on panel IIJ. Band selector 25 is secured to a rod 26 extending into the control unit. A six-position multiple contact switching unit 21 is mechanically coupled to rod 26. A plurality of connection lugs 28 extend from switching unit 21. Fig. '1 shows a rear view of switching unit 21. Connection wires are soldered t lugs 28 in accordance with the circuital design and as required to eiiect the re spective band switching positions. The wires extend to corresponding connections in multiple plug I1, and the corresponding cable connected to the remote radio chassis. The connections for eecting the band switching changes are not detailed herein, since such details are otherwise known in the art. Plug I1 is supported in the unit, and reenforced in position by screws through posts 39 attached in casing Shielded wires I1 as seen in Fig. 3 extend from the rear of plug I1. I

An important feature of the present invention resides in the novel arrangement for simultaneously changing the tuning indications to correspond with the radio frequency band selected. A dial is provided with a plurality of scales calibrated for each of the respective bands. A movable curtain or shutter 30 is arranged to cooperate with dial sheet 3|. Dial sheet 3| contains a plurality of calibrated scales. Curtain 30 has a central rectangular opening 29, designed to expose any one of the plurality of scales 'on dail sheet 3|. Curtain 30 is of ilexible material, such and correspondingly moving curtain 30 in accordance with the positions thereof. Uniform radial movements of pulley 40 for the respective band positions are translated into equal linear movements of curtain 30 through cord 31 to properly position its central opening 29 opposite a selected one of the equally spaced scales on dial 3 I Thus, for any one of the plurality of distinct positions of selector knob 25, the tuning circuits in the remote radio chassis are connected to correspond to the respective radio frequency bands 'by switch 21, and curtain 30 is moved to expose the calibrated scale corresponding to the selected radio frequency band. The dotted position 30' in Fig. 3 indicates a displaced position of curtain 30 from that Aotherwise illustrated.

Another important feature of the present invention resides in extending the individual frequency indicating scales over a long linear path, whereby the individual frequency positions are readily readable by an otherwise busy pilot. An effective band spreading arrangement results, greatly facilitating accurate selection and tuning-in of radio stations by the pilot. Dial sheet for lightness and rigidity, containing holes 49 for as fabric. Its position is controlled by band se- ,35

lector 25 to expose the particular scale corresponding to the selected radio l:frequency band. The selected position shown in Fig. 1 is for band No. 4, corresponding there to the radio frequency band 2.8 to 6.7 megacycles.

The calibrated scales are individually visible through an opening in panel I0 into which a.

transparent pane 32 is mounted. A rectangular escutcheon plate 33 is attached to the panel, indicating the frequency range corresponding to the adjacent scales, and holding pane 32 in place. A verticalV index line 34 is marked on pane 32, serving as the common index for the scales. The scales are moved past index 34 in the tuning, and correspond to the frequency of the remotely tuned radio circuits.

A metal bar 35 is secured to each end of curtain 30. Bars 35 cooperate in tracks or guide strips 36, 36 mounted on a section of the frame.

A cord 31 is attached to each end of curtain 30,

extending about respective pulleys 38, 38 and pulley 40. Pulley 40 is secured to band selector rod 26 for rotation with selector knob 25 and multi-contact switch 21. Cord 31 is preferably of silk to provide high tensile strength and reliable serviceability under varying weather and humidity conditions. Cord 31 is wound about the groove of pulley 46. The central section of cord 31 is passed through a V-notch 4|in pulley 40, and reentrantly wound about. hub 42 of the pulley anchored in post 43. Post 43 contains a. hole through which the doubled-up central region of cord 31 is passed. 'I'he end 44 of post 43 is peenedover to rotatably carry it on pulley 40. Post 43 is rotated to tighten cord 31 in position around pulley 40, whereby its assembly with curtain 30 is rendered taut.

Rotation of selector knob 25 in its six positions correspondingly rotates pulley .40, carrying cord 31 around the peripheral 'groove of the pulley reducing weight. Drums 45, 46 are spaced apart so that the intermediate portion of dial sheet 3| is adjacent to and parallel with transparent pane 32. A lamp 50 is arranged between the drums to illuminate the portion of the translucent dial sheet 3| in front of pane 32. However, only the scale opposite the opening 29 of curtain 30 is visible from the front of control panel I0, corresponding`to the selected band.

A gear-down arrangement is provided wherein the frequency scales on dial sheet 3| are considerably spread out. Tuning knob 5| is operated by the pilot to remotely tune-in the proper sta- `tion, or otherwise adjust the frequency of the receiver circuits to the desired value. Knob 5| is connected with rod 52 rotatably mounted behind panel I0 in frame portion 53 as seen in Figs. 3 and 4. A gear 54 is secured with rod 52, coacting with pinion 55 connected with rod 56. Rod 56 carries worm 51 which coacts with worm gear 56 connected to central shaft 59of drum 45. Rotation of tuning knob 5| in either direction rotates drum 45 correspondingly effecting a substantially reduced turning ratio.

Drum 46 is arranged to rotate in correspondence with drum 45 and hold dial sheet 3| taut.

A spiral spring 60 is attached to shaft 6| of drum 46, shown in detail in Fig. 6. One end of spring 60 is anchored to sha-ft 6|; the other end, to the frame by pin 62. Spring 6 is designed to be substantially wound-up and taut when dial sheet 3| is wound onto drum 45. Drum 46 is rotated in one directionby drum 45 through the pull thus imparted to the dial sheet 3|. The dial sheet is held taut by the tension of spring 60. For tuning in the opposite direction, wound-up spring 60 causes drum 46 to take on dial sheet 3| as drum 45 turns. Dial sheet 3| is thus held taut in the reverse movement as well, and is wound onto drum 46. A friction drag plate unit 63 is connected to worm gear v58 to stabilize the mechanical operation of the tuning drums, and'prevent backlash.

When tuning knob 5| is rotated, the remote ra.

f proportioned to serve as a pinion coacting with the gear 54 operated .by tuning knob 5I. Fluted' shaft 64 is rotatably supported in frame y53, preferably in roller bearings. A iluted extension 65 of shaft 64, of reduced section, extends into externally threaded tube 66. Tube 66 is suitably mounted on cover Il with a block 61, and supported through an opening in the rear of cover I I, as seen in Fig. 3. y

A mechanical shaft or flexible coupling is*v connected to the end of uted rod 65, and assembled by a nipple attached to threaded tube 66, in a manner such as disclosed in my Patent No. 2,317,922. The exible shaft driven with rod 65is directly coupled to the variable tuning element in the remote radio chassis, such as a ganged variable tuning condenser. The scales on dial sheet 3| are respectively calibrated in accordance with the tuning movement of knob 5| and its effect on the radioA circuits. The remote radioset may be a multiple channel radio `receiver, a multiple-band radio direction finder, or

even a tunable radio transmitter, or the like.

Although I have described a preferred embodiment for carryingout the principles of my present invention, it is to be understood that variations and modifications thereof may be practiced by those skilled in the art Without departing from the broader spirit and scope of the invention, as set forth in the appended claims.

What is claimed is`:

A1. In a multiple band radio setz a tuning indi-I.`

cator comprising a dial sheet having a plurality of frequency scales corresponding to the frequency bands of operation of the set; a tuning control coupled to said dial sheet and connectable to the radio set for tuning the radio circuits thereof and correspondingly motivating the dial sheet; a curtain arranged infront of said dial sheet having one opening to expose a substantial portion of any one of the scales; a band selection device comprising a multiple .position switch electrically connectable withthe radio set for con- `trolling the band of operation thereof in accordance with the position selected; and means mechanically connecting said device with said curtain for shifting said opening of the curtain to a position opposite thescale on said dial sheet corresponding to the selected band of radio operation and shielding the other scales from view.

2. A remote tuning control unit. for a multiple band radio set comprising a dial sheet having a plurality of linear scales corresponding toA the frequency bands of operation of the set; a tuning control knob and gearing coupled to said dial sheet and Aconnectable to the radio set for tuning the radio circuits thereof and correspondingly motivating said dial` sheet; a rectangular curtain arranged infront of and transverse to said dial sheet and having one opening to expose a substantial' portion of any one of the scales; a band selection device comprising a multiple position switch electrically connectable with the remote set for controlling the band ofl operation thereof in accordance with the position selected; and means mechanically connecting said device with said curtain for shifting said opening thereof across said dial sheet to a position opposite the frequency scale on said dial sheet corresponding to the selected band of radio operation; whereby the frequency of operation of the radio set is directly indicated with respect to a stationary index of the control unit extending across all the scales. 0

3. A tuning system for a multiple band radio set comprising a tuning dial sheet having a pluralityof calibrated frequency scales individually corresponding to the frequency bands of operation of the radio set; a pair of drums for mounting and carrying said dial sheet in front of a window; a tuning control knob coupled to one of said drums and connectable to the radio set for tuning the radio circuits thereof and correspondingly motivating said dial sheet; a curtain arranged in front of said dial sheet and having one opening to expose a substantial portion of any one of the scales at a time; a band selectiondevice comprising a multiple position switch electrically connectable with the radio set for controlling the band of operation thereof in accordance ywith the position selected; and means mechanically connecting said device with said curtain for shifting said opening of the window; a tuning control knob coupled to saidY dial sheet and connectable to the radio set for tuning the radio circuits thereof and correspondingly motivating said dial sheet; a spring element attached to one of said drums for holding said dial sheet taut; a curtain arranged in front of said dial sheet opposite the dial portion extending between said drums and having an opening to expose a substantial portion of one of the scales at a time: a band selection device comprising a multiple position switch electricallyY connectable with the radio set for controlling the band of operation thereof in accordance with the position selected; and means mechanically connecting said device with said curtain for shifting said opening of the curtain to a position opposite the scale on said dial sheet corresponding to the selected band of radio operation; whereby the frequency of operation of the radio set is directly indicated with respect to a stationary index at said dial sheet.

5. `A tuning system for a multiple band radio `set comprising a tuning dial sheet having a plurality of calibrated frequency scales individually corresponding to the frequency bands of operation of the radio set; a pair of drums for-mounting and carrying said dial sheet in front of a window; a tuning control knob geared to one of said drums and connectable to the radio set for tuning the radio circuits thereof and correspondingly-motivating said dial sheet; a spring wound element attached to the other ofsaid drums for holding said dial taut and for winding the dial sheet on said other drum, and a friction imparting member attached to said one, drum .to stabilize the operation thereof; a curtain arranged in front of said dial sheet opposite the dial sheet portion extending between said drums and-having an opening to expose a substantial portion of one ofthe scalesat a time; a band selection device comprising a multiple position switch electrically connectable with the radio set for controlling the band of operation thereof in accordance with the position selected; and means mechanically connecting said device With said curtain for shifting said opening of the curtain to a position opposite the scale on said dial sheet corresponding to the selected band of radio op` eration; whereby the frequency of operation of the radio set is directly indicated with respect to a stationary index at said dial sheet.

6. A tuning system for a multiple band radio set comprising a sheet containing a plurality of calibrated frequency scales corresponding to frequency band-s of operation of the radio set; drums carrying said sheet; a tuning control geared to said drums and connectable to the radio set for tuning the radio circuits thereof and correspondingly motivating said sheet; an instrumentality arranged in front of and transverse to said sheet and having one opening to expose a substantial portion of any one of the scales corresponding to the band of operation of the set; a band selection device comprising a multiple position switch electrically connectable with the radio set for controlling the band of operation thereof in accordance with the selected position; and a cord and pulley arrangement mechanically connecting saidA device with said instrumentality for shifting said opening thereof to a position opposite the frequency scale Aon said sheet corresponding to the selected band of radio operation; whereby the frequency of operation of the radio set is directly indicated on a stationary index extending across said scales.

7. A tuning system for a. multiple band radio set comprising a sheet containing a plurality of calibrated frequency scales corresponding to frequency bands of operation of the radio set; a pair of spaced drums carrying said sheet; a tuning control geared to one of said drums and connectable to the radio set for tuning the radio circuits thereof and correspondingly motivating said sheet; a spring wound element attached to the other of said -drums for holding said sheet taut and for Winding the sheet on said other drum, and a friction imparting member attached tosaid one drum to stabilize the operation thereof; and a curtain arranged in front of said sheet and having an opening to expose a substantial portion of the one of the scales corresponding to the band of operation of the set.

8. A tuning system for a radio set comprising a linear sheet containing a calibrated tuning scal; a pair of spaced drums carrying said sheet; a. tuning control knob geared to one of said drums and connectable to the radio set for tuning the radio circuits thereof and correspondingly-motivating said sheet; and a spring Wound element attached to the other of said drums for holding said sheet taut and for winding the sheet on said other drum, and a friction imparting member attached to said one drum to stabilize the operation thereof ;v whereby the frequency of operation of the radio set is directly indicated on a stationary index.

l WILLIAM P. LEAR. 

